Facile synthesis of carbon fiber reinforced polymer-hydroxyapatite ternary composite: A mechanically strong bioactive bone graft.

Carbon fiber reinforced carboxymethyl cellulose-hydroxyapatite ternary composites have been synthesized by a simple wet precipitation method for weight bearing orthopedic application. Composites were synthesized with the incorporation of chemically functionalized carbon fibers. The functional groups onto the surface of fibers induced the formation of hydroxyapatite at the bridging position through which fibers were effectively bound with matrix. Consequently, the flexural strength and compressive strength of composite have reached to 140 MPa and 118 MPa, respectively. The flexural modulus of the composite is in the range of 9-22 GPa. In-vitro cell study showed that the composite possesses excellent cell proliferation and differentiation ability. With these excellent mechanical and biological properties, synthesized composite exhibits potential to be used as a mechanically compatible bioactive bone graft.

One pot synthesis of carbon dots decorated carboxymethyl cellulose- hydroxyapatite nanocomposite for drug delivery, tissue engineering and Fe3+ ion sensing.

In this work, carbon dots conjugated carboxymethyl cellulose-hydroxyapatite nanocomposite has been synthesized by one-pot synthesis method and used for multiple applications like metal ion sensing, osteogenic activity, bio-imaging and drug carrier. The structure and morphology of the nanocomposite were systematically characterized by FTIR, XRD, TGA, FESEM, TEM and DLS. Results clearly demonstrated the formation of fluorescent enabled carbon dots conjugated nanocomposite from carboxymethyl cellulose-hydroxyapatite nanocomposite by a simple thermal treatment. The synthesized nanocomposite is smaller than 100 nm and exhibits fluorescence emission band around 440 nm upon excitation with 340 nm wavelength. In the meantime, the nanocomposite was loaded with a chemotherapeutic drug, doxorubicin to evaluate the drug loading potential of synthesized nanocomposite. Moreover, the as-synthesized nanocomposite showed good osteogenic properties for bone tissue engineering and also exhibited excellent selectivity and sensitivity towards Fe3+ ions.

Three dimensional biphasic calcium phosphate nanocomposites for load bearing bioactive bone grafts.

Mimicking matrix mediated bio-mineralization process, three dimensional blocks of biphasic calcium phosphate (BCP, hydroxyapatite (HA) and ß-tricalcium phosphate (TCP)) nanocomposites, having three different stoichiometries have been synthesized for possible application as load bearing synthetic bone graft or scaffolds. Biphasic blocks with three weight ratios of 20:80, 25:75 and 30:70 of HA and TCP respectively have been synthesized. Detailed structural and chemical characterization of the samples revealed a strong dependence of porosity and mechanical properties on the stoichiometry of biphasic blocks. Effect of physiological medium on the microstructure and mechanical properties of the three different blocks has also been studied. Bioactivity of the BCP block, exhibiting highest compressive strength in air as well as in physiological medium, has been evaluated through adhesion, proliferation and differentiation of mesenchymal stem cells using different markers.

Biomimetic nanocomposites of carboxymethyl cellulose-hydroxyapatite: novel three dimensional load bearing bone grafts.

An innovative biomimetic synthesis of novel three dimensional micro/macro porous carboxymethyl cellulose (CMC)-hydroxyapatite (HA) nanocomposites having four systematically different compositions has been established for its possible application as a load bearing synthetic bone graft. Our process, being in situ, involves a simple and cost effective route akin to a matrix mediated biomineralization process. Developed synthesis route not only controls the size of HA particles in the range of 15-50 nm, embedded in CMC matrix, but also assists in the formation of a mechanically strong three dimensional nanocomposite structures due to physical cross linking of HA impregnated CMC matrix. The process does not involve any toxic cross linker and works at near ambient conditions. The nanocomposites are systematically structurally and mechanically characterized using various techniques like scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform IR (FTIR), solid state (13)C nuclear magnetic resonance ((13)C NMR), thermo-gravimetric analysis (TGA) and Universal mechanical test. It reveals that the ionic/polar or electrostatic interactions are the main driving force for formation of load bearing three dimensional nanocomposites via a process similar to matrix mediated biomineralization. Compressive strength and compressive modulus of nanocomposites, being in the range of 1.74-12 MPa and 157-330 MPa, respectively, meet the desired range of compressive strength for the synthetic grafts used in cancellous bone. An increase in the compressive strength with increase in the porosity has been an interesting observation in the present study. In vitro cytotoxicity of the synthesized nanocomposites has been evaluated using bone marrow mesenchymal stem cells (BMSC) isolated from Wistar rat.

Synthesis of injectable and cohesive nano hydroxyapatite scaffolds.

Biomimetically synthesized nanosized hydroxyapatite particles have been converted into an injectable paste using a neutral phosphate buffer. Synthesized system manifested a self setting behavior at 37°C in 20 min and revealed a macroporous self assembled microstructure. Stability of the injectable hydroxyapatite has been confirmed in aqueous medium as well as in human blood. Effect of ball milling was also studied on the stability of the system.